The Senate on Wednesday delivered a historic rebuke of Saudi Arabia and President Trump’s handling of the fallout over journalist Jamal Khashoggi’s killing last month, as a decisive majority voted to advance a measure to end U.S. military support for the Saudi-led war in Yemen.

The 63-to-37 vote is only an initial procedural step, but it nonetheless represents an unprecedented challenge to the security relationship between the United States and Saudi Arabia. The vote was prompted by lawmakers’ growing frustration with Trump for defending Saudi Crown Prince Mohammed bin Salman’s denials of culpability in Khashoggi’s death, despite the CIA’s finding that he had almost certainly ordered the killing.

Their frustration peaked shortly before Wednesday’s vote, when senators met behind closed doors to discuss Saudi Arabia, Khashoggi and Yemen with Secretary of State Mike Pompeo and Defense Secretary Jim Mattis — but not CIA Director Gina Haspel, who did not attend the briefing.

Her absence so incensed lawmakers that one of the president’s closest congressional allies threatened not only to vote for the Yemen resolution but also to withhold his support from “any key vote” — including a government funding bill — until Haspel was sent to Capitol Hill for a briefing.

“I am not going to blow past this,” said Sen. Lindsey O. Graham (R-S.C.). “Anything that you need me for to get out of town — I ain’t doing it until we hear from the CIA.”

In a statement, CIA spokesman Timothy Barrett said “the notion that anyone told Director Haspel not to attend today’s briefing is false.” He added that Haspel, who traveled to Turkey to listen to a recording of Khashoggi’s killing and review evidence in the case, had fully briefed congressional leaders and members of the Senate Intelligence Committee.

Secretary of State Mike Pompeo and Defense Secretary Jim Mattis sought to make a case for continuing U.S. support for Saudi Arabia’s military campaign in Yemen. (Joshua Roberts/Reuters)

But only one of the 14 Republicans who voted to move ahead with the Yemen resolution has been briefed. Trump, Pompeo and national security adviser John Bolton all have pointedly said they have not listened to the tape, and see no reason to do so.

The pressure is now squarely on Trump not just to dispatch Haspel to the Hill but also to take concerted steps to hold Mohammed accountable before the Senate makes its next move, which is likely to come next week.

“There’s ways that the administration, even rhetorically, can help change the dynamic,” Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) said shortly before Wednesday’s vote. He added that while “Saudi Arabia is an ally, of sorts, and a semi-important country, we’ve watched innocent people be killed. . . . We also have a crown prince who is out of control.”

The White House and Senate have been tiptoeing toward a standoff over Saudi Arabia for more than a year, as an increasing number of senators have backed efforts to halt certain arms sales or end other military support for the Saudi-led coalition battling Iranian-backed rebels in Yemen. But the willingness to formally admonish Saudi Arabia grew after Khashoggi, a contributing columnist for The Washington Post, was killed inside the Saudi Consulate in Istanbul and the Trump administration took what many have seen as only modest steps to pursue accountability.

If Trump takes more aggressive action over the weekend, it could keep senators such as Corker from voting to start a debate on the Yemen resolution. But with 63 senators on board now, it is unclear whether Trump can do enough to stop the Yemen resolution from proceeding.

To date, Trump’s deputies have shown no indication of planning to change course.

Earlier Wednesday, both Pompeo and Mattis framed U.S. support for Saudi Arabia as a national security matter, even though Riyadh’s conduct in the civil war in Yemen has drawn international condemnation.

Pompeo struck an unapologetic tone, arguing that without U.S. involvement, the humanitarian crisis there and the threat posed to U.S. interests and Americans “would be a hell of a lot worse.” He also argued that the resolution could thwart negotiations to secure a cease-fire — an argument lawmakers disputed.

“All we would achieve from an American drawdown is a stronger Iran and a reinvigorated ISIS and al-Qaeda in the Arabian Peninsula,” said Pompeo, using an acronym for the Islamic State. “Try defending that outcome back home.”

In a Wednesday opinion piece in the Wall Street Journal, Pompeo characterized the reaction to Khashoggi’s slaying as “Capitol Hill caterwauling and media pile-on.” Pompeo did not mention Khashoggi in his prepared remarks to senators.

Mattis lamented the journalist’s killing while underscoring the need to continue a partnership with Saudi Arabia even as the airstrikes have killed tens of thousands of people, both civilians and rebels.

“We are seldom free to work with unblemished partners,” Mattis said. “Long-standing relationships guide but do not blind us. Saudi Arabia, due to geography and the Iranian threat, is fundamental to maintaining regional and Israeli security, and to our interest in Mideast stability.”

As pressure to reduce U.S. military ties with the Saudis has increased, Riyadh has emphasized that it has other options, including with Russia. But lawmakers have tired of such strategic arguments, arguing that Trump should prioritize the defense of American human-rights ideals — such as condemning the killing of a journalist — over the expedient of looking the other way.

“I’m all for realpolitik, but that suggests that you accept the truth,” Sen. Jeff Flake (R-Ariz.) said of Khashoggi’s death, adding that if Mohammed “wasn’t directly involved, he certainly knew of it.”

The resolution, drafted by Sens. Bernie Sanders (I-Vt.) and Mike Lee (R-Utah), seeks to invoke the War Powers Act to end U.S. military support for the ­Saudi-led coalition, which human rights groups accuse of fomenting in Yemen the world’s worst humanitarian crisis. If the push is successful, it will be the first time since the act was passed in 1973 that it has been used to end a foreign operation — putting the Senate in somewhat uncharted legislative territory.

Several Republicans guessed that senators would try to soften the resolution with amendments. But some worry that the effort could spin out of control.

“This would be a process like the budget vote-a-rama,” Corker said, referring to round-the-clock amendment votes that regularly accompany the budget process. “Except we’re firing with real bullets; these are real laws.”

Even if the Senate passes the resolution, it stands little to no chance of clearing the House, where GOP leaders already intervened once this month to block members from voting on a similar measure. Senate leaders may also pressure lawmakers to hurry through the resolution process, lest it complicate a Dec. 7 deadline to pass a bill to fund the federal government.

Some Republican senators surmised that if momentum builds around the Yemen resolution, leaders could feel compelled to include punitive measures against Saudi Arabia in the must-pass funding bill. Several senators from both parties think the funding measure could be a vehicle for bipartisan-backed proposals to end arms transfers to Saudi Arabia and impose sanctions on those implicated in the conflict in Yemen.

Karoun DemirjianKaroun Demirjian is a congressional reporter covering national security, including defense, foreign policy, intelligence and matters concerning the judiciary. She was previously a correspondent based in The Post's bureau in Moscow. Follow

Carol MorelloCarol Morello is the diplomatic correspondent for The Washington Post, covering the State Department. She previously wrote about demographics and the census. She has worked at The Post since 2000. Before that, she was a reporter for the Philadelphia Inquirer and USA Today. Follow

John HudsonJohn Hudson is a national security reporter at The Washington Post covering the State Department and diplomacy. He has reported from a mix of countries including Ukraine, Pakistan, Malaysia, China, and Georgia. Follow